The integrated circuits within computer (or server) systems are powered by multi-output power supplies that provide Direct current (DC) voltages. Currently, most of the computer systems have comparatively low power requirements for each of the voltages produced by the power supply (e.g., less than safety limit 240 VA (or 20 A current for a 12V rail)) for sufficient operation.
Such comparatively low power deliveries are not hazardous to a user, and thus an overcurrent (or overpower) protection limit may be set below this level which meets safety standard requirement and prevents any injures to the user that has access to the power supply circuit. However, a new generation of integrated circuits (e.g., processors) have power requirements that exceed 240 VA. Consequently, it is necessary to protect power supply circuits (primarily the +12V rail) accessible by a user against exceeding this power level in order to prevent injuries to the user.
One method of protecting against exceeding safety power limit accessible to the user in high power systems is to divide (split) the 12V rail into two or more rails. This method of protection is feasible for systems where the load may also be split into several independent load channels. In such cases, each of these channels would have individual 240 VA protection circuitry, but combined power delivered by all the channels may exceed this level.
Each protection circuit either limits the power at a lower level (below 240 VA), or almost instantly shuts the power supply off once the 240 VA limit is exceeded on any of the rails. However, splitting the loads and outputs into several rails, e.g., adding the channels, increases the power supply and system cost. Furthermore, this is only a viable option in cases where two or more integrated circuits are supplied. In instances where a single integrated circuit, such as a single processor, requires the full power delivery, other solutions are required.
One such solution is to introduce mechanical barriers to the computer system to prevent users from accessing the power supply circuit. However, the implementation of mechanical barriers increase the manufacturing costs of computer systems.
Another solution is to restrict access of the computer system to specially trained personnel. In most instances, such an alternative is unacceptable since the trend of computer systems is to be accessible to users.